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THE ACTD BESSEMER PROCESS.                              109
lower content of silicon is practicable.    The manufacture of this hard steel is made feasible by the low phosphorus and low sulphur
TABLE VI-E. Calorific History of the Acid Converter.
Data:    1000 kg. pig-iron; Si=1.00 per cent.; C=3.50 per cent. Initial temperature=1400 C.    Average temperature about 1600° C. Loss=8 per cent.   Metallic iron burned=2 per cent. Specific heat at 1600° C., per cubic metre CO and N=0.40; C0z=1.34. Specific heat at 1600° C., per kilo liquid steel 0.21, liquid slag 0.25, lining 0.25; per kilo CO and N=0.32, CO2=0.68.
Specific heat of air 100" C. to 1400° C., per cubic metre=0.346; per kg.=0.268.
Combustion of Silicon—                           Calories.        Surplus.
10 kg.  Si+11.4 kg. O=21.4 kg.  8102=64,140 11.4 kg. O=49.6 kg. air, absorbing
49.6X0.268X1300                        =17,280           46,860
Combustion of Iron—
20 kg. Fe+5.7 kg.  0=25.7 kg.  FeO=23,460 5.7 kg. O=24.8 kg. air, absorbing
24.8X0.268X1300                        =  8640           14,820
Combustion of Carbon—
7  kg.   C+18.7 kg.  O=25.7 kg.  002=56,930 28  kg.   C+37.3  kg.  0=65.3 kg.   C0=68,600
125,530 56 kg. O=243.5 kg. air, absorbing
243.5X0.268X1300                      =84,830           40,700
Total surplus heat developed........                   102,380
CALORIFIC  CAPACITY OF THE PRODUCTS. WeightXSp. heat at 1600 degrees. 920 kg.liquid steelX0.21         =193.2. 150 kg. liquid slagX0.25         == 37.5 50 kg. lining         X0.25         = 12.5 25.7 kg. COS          X0.68X3/4 = 13.1
65.3 kg. CO           X0.32X3/4 = 15.7
244.8 kg. N             X0.32X1/2 = 39.2
Total capacity per 1° C.       =311.2
102 380 Theoretical rise of temperature=   _ '   2 =329* C.
in Swedish irons, and although interrupting the blow gives irregular results the steel can be graded after it is made. The failure of the direct metal process in other countries arose from irregular blast-furnace work. By allowing the iron to become cold and mixing the different.qualities, it was possible to get a more regular metal. Direct metal is practicable to-day mainly because of ini-